MONDAY, Oct. 29, 2018 (HealthDay News) -- It's the most frustrating part of dieting: Regaining the weight you worked so hard to lose.

It helps to understand why this happens so you won't blame yourself as you get back on track.

Many hormones that regulate body weight and rule your appetite seem to go haywire after weight loss, possibly because the body wants the weight it was familiar with back on. These hormones can stay higher, encouraging weight regain, for more than a year, even after the pounds start creeping back.

So the tendency for weight regain could be part of the body's natural instinct and not simply because you went back to old eating habits. To combat this, you need to keep a diet mindset for at least one year after you reach your goal weight.

But what can you do if that weight has already started coming back? First, go easy on yourself. Dieting takes dedicated effort and you don't want to waste energy blaming yourself.

Next, go back to all the diet principles that helped you lose weight. Do a self-checkup to see if your portions have gotten bigger recently, if you're eating too often, or if you're not being as careful about the quality of calories you choose as you were when you were losing weight.

It may also be that you aren't exercising as much as you did. While calorie restriction seems to increase appetite, exercise can reduce it as well as burn off calories. A study published in the Annals of Nutrition and Metabolism found that exercising after a meal may extend the feeling of satisfaction that the food gave you. This could be helpful in coping with smaller portions.

Just be sure not to overeat right before exercise. A small snack is OK, but you should wait two hours after a full meal so that digestion isn't fighting against your workout efforts.